Explosive rivet gun tip assembly



1952 P. B. RAKOWSKI, JR

EXPLOSIVE RIVET GUN TIP ASSEMBLY Filed March 9, 1949 grwemfo'o til wow,

Patented Jan. 8, 1952 .nxPLosrvE RIVET GUN- TIP. ASSEMBLY Paul BtRakowskL'Jn, Baltimore, Md., assignor to The-Glenn L.Martin Company,Mi'ddle River, Md., a corporation of Maryland Application ,March..9, 1949, Serial No. 80,491

1 Claim. Til

' This'invention relates generally'to the art of working "explosive rivets and, moreparticularly, to an improved explosive" rivet gun tipassembly.

The use of explosive rivets having a hollow shank spaced inwardly of "a head'portion and filled-with a heat sensitive explosive, adapte'cl to be exploded on application of a predetermined amount of heat to thehead, has'becomea common practice. Furthermoregin order to attain high speed production it is'highly desirable that the time required 'to explode such a :rivet 'be as'short as possible. However, one of the'problems of working explosive rivets is to avoid'prematureexplosion of 'the rivet chargebefore the rivet. is properly seated. This occurs if 'for any reason"the.rivet does not .properly seat -as:it is being'heated. iThusly, the normal exploding time' ofrthe rivet is consumed in theattempt ofithe worker ,to position the rivet by ;means :of the heated gun. With. the :conventional'type :of: rivet exploding gun or iron, :the "explosive :rivet .is seated'and exploded by having the hot tip :of the'gun pressed thereagainstas one-operation. Once the heating of the rivet is started,..even though the "rivet fails to align properly .in the rivethole, the operator has no alternative. other than .to'hold the rivet gun in contact with the rivet until it explodes so as to avoid 'the risk ofhaving the rivet explode in hisvface-uponremoval of the gun. .Arivet soexploded, not only constitutes a defective rivet that must .be v'replaced, but, also, may .result indamage to .the sheet materialbeing riveted. In eitherease, the cost of replacement or repairiisnot only .costly in .time but seriously delays the working schedule of such an operation.

My inventionprovideseasolutionito these problems by providing an improved explosive rivet g'u'ntip assembly having a" movable ring mounted forwardly of the heated end of arivet gun "as a guard againstprematurecontact or said heated portion with a rivet head centered therein .and adapted to allow forward movement .of the heated rivet gun end into engagement with the center of the rivet head to explode iton application of additional predetermined force to the un.

It isioneof the objects of this invention to provide an apparatus for controlling exploding of-explosive rivets so as to avoidthe dangers and disadvantages of theconventiona'l type of rivet exploding gun, having an unguarded hot tip.

Anotherobject is to provide an explosive .riveting device wherein a rivet engaging pressure pad is spaced forwardly of a rivet heating membe capable of axial movement within the pressure pad to effect engagement-with the rivet on the application of 'force'applied axially of the rivet gun.

Still another object is to provide explosive-rivet detonating means wherein the detonating member is sheathed within a rivet engaging ring.

,A still further object is'to prevent premature or accidental explosion of explosive rivet bysequentially engaging and holding said rivet and applying heat thereto.

Another object is to provide :a riveting gun having a wear-resistant rivet head engaging means mounted "forwardly of a rivet engaging tip.

'Other objects of this invention will become apparent from the following description when taken in conjunction with .the accompanying drawing, in which like numbers refer to like parts-in di'flerent views.

In the drawing:

Fig. lis a sectional view or the present inventioninstalled on a conventional type. of hot rivet gun fragmentarily. shown.

Fig. 2 is a5sectional view of the device showing thepressure'ring in encircled engagement with .a.rivet head :and the rivet exploding ortion 10f the rivet gun in aligned engagement withsaid rivet.

.Fig.3.is an .end view of the device taken on line 3-13 Of Fig. 11.

.Referringqmore particularly to Fig. l, the device oi this invention is comprised of a housing l0:adapted.fonsleeve-like mounting over the end oia.conventionaltype of. hot rivet-gun I I having an iron portion t2 arranged as a rivet heating iron adapted for movementwithin the housing to engage a :rivet head and conduct heat thereto. The-riVetJheating iron 52 is generally that of a iconventionaltype of rivet exploding gun and is preferablymadeof copper or analloy metal characterized by its high heat conductivity. .Rearwardly :of the iron I2 .is a barrel portion ,l3 having an increased cross-section with a shoulder 26 formed adjacent the iron. Both the iron 12 .and the barrel portion 53 are adapted .for insertion in the gun H in a conventional manner such asby threaded engagement therewith. .Iheiron I2 is heated by a conventional .typeof heatingunit 28 placed interiorly of the gun;,l l with one end of the heater being extended within the iron for conduction of heat thereto. Theheating unit 2 8:is energized from a suitable electrical supply circuit (not shown) ,Inthe extreme ,forward :end of hot iron portion I2 is a concaved point 11 adapted for matched engagement with the rounded head of an explosive rivet. The housing II) is formed generally cylindrical of a suitable lightweight metal such as aluminum so as to add as little additional weight to the gun assembly as possible. The inner dimensions of the housing are arranged to provide a slide fit over the hot iron portion 12 and the barrel [8 with the concaved point portion of the iron centered thereto. Limited axial movement of the housing l0 relative to the gun i l is provided by a longitudinally extending closed-ended slot 58 formed in the outer surface of the barrel [3 of the gun into which the end 25 of a set screw i5, carried by the housing l8, protrudes.

Positioned around the iron 52 is a spring i4 placed in compression between a shoulder 26, formed inwardly and normal to the barrel i3, and an abutment 27 formed internally of the housing I0. In this manner, the urge of spring is having one end positioned against the shoulder 28 of the gun and the other end positioned against the abutment 27 carried by the housing, tends to urge the housing forwardly to sheath the hot iron [2 to the extend provided by the closed slot i6 into which the set screw l protrudes. Forward movement of the iron relative to the housing is readily accomplished by the exertion of sufiicient pressure against the gun M with the housing held against forward movement to overcome the urge of spring 14.

The outer end of the housing It is formed with a threaded portion 18 adapted to receive a circular insert l9 proportioned to overhangingly engage the outer periphery of a rivet head to be riveted. This is best illustrated in Fig. 2 which shows the insert l9, having its inner diameter smaller than the outside diameter of the rivet head, positioned in peripheral engagement with the head of an explosive rivet 20, having a shank portion 2! inserted through metal sheets 22 and 23 for riveting. This arrangement of the insert 19 is used to properly seat the rivet 20 with'the head in engagement with the outer surface of the sheet 22 as the gun iron I2 is forced forwardly against the compression spring M. The inner periphery of the insert i9 is slightly greater than the outer periphery of the end of iron 12 to provide for free movement of the point i! into engagement with a rivet head centered within the insert. The sheathing effect of the hot end I2 of the rivet gun not only guards against accidental heating of a particlular rivet but also the adjacent rivets of a rivet assemblage. Undue wear of the point i7 is also avoided as contact between it and the rivet being worked is limited to an aligned pressure engagement.

The insert [9 is preferably formed of wearresistant hard metal as compared with the soft metal of the heating iron which provides for long services without an appreciable change in dimensions so as to effect the heat transfer characteristics of the gun. The insert, being removable, also provides for a plurality of tip sizes necessary in the working of different sized rivets.

Figure 3'shows the cooperative relationship of the concaved point if relative to the insert I9 adapted for centering over a rivet head to be riveted, The point I! is so centered with relation to the insert i9 that uniform engagement of the rivet head is assured which tends to produce a more uniform riveting operation.

The operation of my device when installed in combination with a suitable rivet gun is that the hot iron portion I2 is drawn within the housing fully surrounded by the housing and the rivet explosion starting time is accurately controlled as there can be no accidental heating of the rivet.

Although my invention has been shown and described in considerable detail, it will be appreciated that certain changes, alterations, modifications, and substitutions can be made without departing from the spirit and scope of the claim.

I claim as my invention:

A tool for heating the head end of explosive rivets comprising a rivet heating gun havinga main body portion, a tip member of high heat conductivity rigidly carried by said body portion and extending axially forwardly therefrom, said tip member having a forward portion of one diameter and a rear portion of a larger diameter providing an external circumferential shoulder, and heating means carried within the said body for heating said tip member to a relatively high temperature, a sleeve-like housing slidably car ried directly on said tip member for only limited axial movement relative thereto, said housing including an internal circumferential shoulder in axial alignment with the shoulder of the tip member, and a seating ring of wear-resistant material secured to said housing and extending forwardly thereof and being providedwith an opening extendin axially therethrough whereby to provide a pressure surface surrounding said opening adapted for applying force axially forwardly directed, and spring means positioned between said shoulders normally urging said housing forwardly relative to said tip member, means for stopping such forward movement of the housing at a position wherein said tip member is spaced axially inwardly from said pressure surface, said gun being movable forwardly against the reaction of said spring means when said seating surface is held against forward movement whereby the forward end of said tip member will be moved into close proximity to said seating surface and into position to contact the head of such a rivet extending rearwardly into said opening for applying heat thereto. I

PAUL B. RAKOWSKI, JR.

REFERENCES CITED The following references are of record the file of this patent: 

